Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/.travis.yml

 sudo: required
 # Note: travis currently does not support listing more than one language so
 # this cheats and claims to only be cpp.  If they add multiple language
 # support, this should probably get updated to install steps and/or
 # rvm/gemfile/jdk/etc. entries rather than manually doing the work.
 language: cpp
 os:
   - linux
   - osx
-# The Objective C build needs Xcode 6.4 or later.
-osx_image: xcode7.1
+# The Objective C build needs Xcode 7.0 or later.
+osx_image: xcode7.2
 script:
-  - ./travis.sh $CONFIG
+  - ./tests.sh $CONFIG
 env:
   - CONFIG=cpp
   - CONFIG=cpp_distcheck
   - CONFIG=csharp
   - CONFIG=golang
   - CONFIG=java_jdk6
   - CONFIG=java_jdk7
   - CONFIG=java_oracle7
   - CONFIG=javanano_jdk6
   - CONFIG=javanano_jdk7
@@ skipping 36 matching lines @@
     - os: osx
       env: CONFIG=objectivec_ios
     - os: osx
       env: CONFIG=objectivec_osx
   allow_failures:
     # These currently do not work on OS X but are being worked on by @haberman.
     - os: osx
       env: CONFIG=ruby22
     - os: osx
       env: CONFIG=jruby
+    # https://github.com/google/protobuf/issues/1253 - Started failing when
+    # we moved to an OS X image that is 10.11.
+    - os: osx
+      env: CONFIG=python_cpp
+    # xctool 0.2.8 seems to have a bug where it randomly kills tests saying
+    # they failed.
+    #   https://github.com/facebook/xctool/issues/619
+    #   https://github.com/google/protobuf/issues/1232
+    # travis updated their images to include 0.2.8:
+    #   https://blog.travis-ci.com/2016-03-23-xcode-image-updates
+    # Mark the iOS test as flakey so these failures don't turn things red.
+    - os: osx
+      env: CONFIG=objectivec_ios
 notifications:
   email: false